Intravenous anesthetics are used for anesthesia, which is simple and fast. When the drug reaches the brain after intravenous injection, anesthesia occurs, and the induction period is not obvious. Because anesthesia is shallow, it is mainly used to induce anesthesia. If used alone, it is only suitable for minor surgery and some surgical treatments. (thiopental sodium)

High fat solubility and fast anesthetic effect, but short duration, poor analgesic effect and incomplete muscle relaxation. Clinically, it is mainly used for induction anesthesia, basic anesthesia and short-term minor surgery. (ketamine)

NMDA receptor blockers can block pain conduction and excite brain stem and limbic system. It is called separation anesthesia to make the pain disappear while some consciousness still exists. It has obvious exciting effect on cardiovascular system. Clinically, it is mainly used for minor body surface surgery. It has little influence on cardiovascular system and is suitable for anesthesia of the elderly, children and patients with neurosurgery, trauma and burn. Muscle laxity is usually used in combination with muscle relaxants and diazepam. It is also used to induce anesthesia. Patients with severe hypertension, atrioventricular block and epilepsy are prohibited.